Avalanche Advisory for Saturday, January 31, 2015 Expires tonight at 12:00 midnight Very dangerous avalanche conditions exist in Tuckerman and Huntington Ravines. Travel in avalanche terrain, including low angle terrain in the floor of the Ravines, is not recommended. Tuckerman Ravine has High, Considerable, and Moderate avalanche danger. Sluice, Lip, and Center Bowl have High avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. Lobster Claw, Right Gully, Chute, Left Gully, and Hillman’s Highway have Considerable avalanche danger. Natural avalanches are possible and human-triggered avalanches are likely. Careful snowpack and weather evaluation, cautious route finding and conservative decision making are essential. Little Headwall and the Lower Snowfields have Moderate avalanche danger. Natural avalanches are unlikely and human-triggered avalanche are possible. Huntington Ravine has High and Considerable avalanche danger. Damnation, Yale, Central, and Pinnacle have High avalanche danger. Natural avalanches are likely and human-triggered avalanches are very likely. North, Odell, South, and Escape Hatch have Considerable avalanche danger. Natural avalanches are possible and humantriggered avalanches are likely. AVALANCHE PROBLEM: Wind slabs are the imminent threat today. New snow deposited on near calm winds yesterday will form a soft weak layer on which new wind slabs will form today. These slabs will continue to build through the day and could avalanche spontaneously from lee areas without a human to trigger them. Avalanche paths are developed to the point that avalanches will likely run out onto low angle and flat terrain therefore travel into the vicinity of the Fan in Huntington or into the floor of Tuckerman much beyond the Connection Rescue Cache is not recommended. WEATHER: 5.5” (13.4cm) of new snow was observed on the 24 hour board this morning at the Hermit Lake snow plot. The summit recorded a similar figure that of 5% density snow which will be easily blown into our avalanche starting zones. It is a serious day to be in the mountains. High winds ramping up from 60ish mph to 7595mph (121-153kph), gusting to 110mph (177kph), frigid temperatures around -5F (-21C), low visibility and elevated avalanche risk make it a very challenging day. SNOWPACK: Hopefully you are not thinking that areas rated Considerable are the better target for recreation today. Though the risk of natural avalanches in these areas is less than in areas rated High, you could still easily trigger a sizable avalanche. New snow over the past 24 hours has formed a sensitive weak layer with wind slabs on top that will be soft enough to trigger pretty easily. Today’s wind will ramp up and continue the process of creating denser slabs over a softer, weaker layer. Bear in mind too that there is still snow from the Tuesday event earlier in the week that will be available for transport due to the short period of time that high winds were able to effect it. Later today, wind velocities will increase to the point that snow deposited earlier during this storm cycle will begin to erode, especially in Huntington Ravine. Though the avalanche danger will diminish at that point, there many other factors that should make you consider your travel decisions very carefully. The Lion Head Winter Route is open but will present a significant challenge today given the current weather conditions and forecast. A minor incident could turn into a life or death struggle. Please Remember: Safe travel in avalanche terrain requires training and experience. This advisory is just one tool to help you make your own decisions in avalanche terrain. You control your own risk by choosing where, when, and how you travel. Anticipate a changing avalanche danger when actual weather differs from the higher summits forecast. For more information contact the Forest Service Snow Rangers, the AMC at the Pinkham Notch Visitor Center, or the caretakers at Hermit Lake Shelters or the Harvard Cabin. Posted 8:15a.m. Saturday, January 31, 2015. A new advisory will be issued tomorrow. Frank Carus, Snow Ranger USDA Forest Service White Mountain National Forest (603) 466-2713 TTY (603) 466-2856
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